Surgical staplers, such as utilized in anastomosis procedures, transection of tissue, and other procedures, generally include one or more staples and an anvil against which those staples are deformed. Surgical staplers often additionally include a knife that is used to cut tissue after, during or before staples are deployed adjacent to that tissue. For example, U.S. Pat. No. 7,285,131 and U.S. patent application Ser. No. 11/935,315 filed on Nov. 5, 2007, both of which are hereby incorporated by reference in their entirety (the “Anvil Documents”) describe an anvil sized for placement in a target blood vessel, where staples are deployed from outside the coronary artery against the anvil to connect a graft vessel to the target vessel. The anvils disclosed in the Anvil Documents each include a knife, and a channel along which the knife can slide. The knife is initially in a first position stowed inside the anvil, then moves to a position above the anvil in order to cut the wall of the target vessel and allow blood to flow between the graft vessel and the target vessel, thereby completing the anastomosis. The knife is then moved back to a second position stowed within the anvil, different from the first position. The Anvil Documents describe single-user tools that cannot be refired. One reason is that the first and second stowed positions of the knife within the anvil are different.
The use of the same reference symbols in different figures indicates similar or identical items.